<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>page-b</title>
</head>

<body>
  <header class="header">
  <h1>page-a header</h1>
</header>


  <nav>
    <a href="/">home</a>
    <a href="/page-a/sub-a/">subpage-a</a>
    <a href="/page-a">page-a</a>
  </nav>

  <main>
    <h1>page-a content</h1>
  </main>

  <footer>
  <h1>page-a footer</h1>
</footer>
</body>

</html>